Best carburetor for 86' 460 7.5L

[ramses]

Hello guys,

Getting back on the F350 after a couple of months downtime. Not ready to fire her up yet, but close. So I know very little about carbs. Can't tell which one I have installed or how old it is, but figured I should have it check or rebuilt since I'm fixing up the rest. Got me thinking if a specific carburetor has been best combination for this engine for fuel efficiency. This will be a work truck so not looking for speed. Any input would be appreciated.

[Gary Lewis]

I'm sorry, but you implied a 7.5L, aka 460, in the same paragraph as "efficiency". I think if you look in your Funk & Wagnalls you'll find that is a faux pas.

Seriously though, my 460 was fine with a 600 CFM Edelbrock but had more high-RPM go with a 750 Eddy. So anything between those two limits would work. And I like Edelbrocks better than Holleys, but that's a personal preference.

[grumpin]

I'm sorry, but you implied a 7.5L, aka 460, in the same paragraph as "efficiency". I think if you look in your Funk & Wagnalls you'll find that is a faux pas.

Seriously though, my 460 was fine with a 600 CFM Edelbrock but had more high-RPM go with a 750 Eddy. So anything between those two limits would work. And I like Edelbrocks better than Holleys, but that's a personal preference.

I put one of these Holley’s on mine. The linkage fit as factory.

https://www.holley.com/products/fuel_systems/carburetors/street/parts/0-80457S

[ArdWrknTrk]

You're going to find the stock 4180 Holley (for Motorcraft) carburetor is the most fuel efficient carburetor that can be had for a fairly stock 460.

Ford engineering and Holley spent a lot of time and money to squeeze the cleanest driveable mixture out of it.

The two stage Power Valve offers just enough fuel with the throttle open, and the accelerator pump cam just enough shot for acceleration without any stumble.

Having a functional EGR is a big part of that.

Without EGR there is no way to achieve a mixture that lean under cruise.

I say this as someone who has owned my pickup for 34 years, and used the 4180, the 0-80457-S, a Edelbrock 650* AVS, and this 750 Holley 4160.

I also use my truck for work and just put $110 in fuel into it on the way home, so it is not as if I don't feel the sting.

But Gary is right, any 460 truck with a GVW over 8,500 is going to be fortunate to see better than 12 mpg.

And if you are working one with a worn engine you will be lucky to get better than 10.

Load doesn't matter much if you have a high gear ratio.

Drag does at highway speeds.

Lifts and big tires get too much air under the truck.

It's best to run it at your best rpm for bsfc and not worry about the rounding errors.(ie, don't lug the engine) you lose too much if your engine is sucking against a closed throttle.

One good change you can make if you don't have emissions inspections is to replace the timing set for a true double roller without cam retard, like was installed in the later '88^ EFI engines.

 

[Fryeken]

You're going to find the stock 4180 Holley (for Motorcraft) carburetor is the most fuel efficient carburetor that can be had for a fairly stock 460.

Ford engineering and Holley spent a lot of time and money to squeeze the cleanest driveable mixture out of it.

The two stage Power Valve offers just enough fuel with the throttle open, and the accelerator pump cam just enough shot for acceleration without any stumble.

Having a functional EGR is a big part of that.

Without EGR there is no way to achieve a mixture that lean under cruise.

I say this as someone who has owned my pickup for 34 years, and used the 4180, the 0-80457-S, a Edelbrock 650* AVS, and this 750 Holley 4160.

I also use my truck for work and just put $110 in fuel into it on the way home, so it is not as if I don't feel the sting.

But Gary is right, any 460 truck with a GVW over 8,500 is going to be fortunate to see better than 12 mpg.

And if you are working one with a worn engine you will be lucky to get better than 10.

Load doesn't matter much if you have a high gear ratio.

Drag does at highway speeds.

Lifts and big tires get too much air under the truck.

It's best to run it at your best rpm for bsfc and not worry about the rounding errors.(ie, don't lug the engine) you lose too much if your engine is sucking against a closed throttle.

One good change you can make if you don't have emissions inspections is to replace the timing set for a true double roller without cam retard, like was installed in the later '88^ EFI engines.

Of the four carbs you’ve ran, which did you like best?

A friend years ago had an old 780 double pumper on a 85 460 with a four speed. Jetted with 74’s front and back. Great difference

I’m looking to replace the stock 4180- or at least I need to do some work to get everything running smooth.

[ArdWrknTrk]

Of the four carbs you’ve ran, which did you like best?

A friend years ago had an old 780 double pumper on a 85 460 with a four speed. Jetted with 74’s front and back. Great difference

I’m looking to replace the stock 4180- or at least I need to do some work to get everything running smooth.

I definitely wouldn't use a carb with mechanical secondaries in a heavy truck on the street.

"Feels fast" and is fast are two different things.

"Like" is subjective. I like them all!

The 4180 probably metered best with the stock cam and all emissions in place.

The RV cam was a step backwards over the factory cam set straight up.

The 0-80457-S was a good replacement for the worn out 4180.

Do you use your truck for work? To tow?

Is it 4wd, and do you use it off road?

Automatic or manual transmission?

What axle ratio and tire size?

Do you have the stock cam, intake and exhaust manifolds?

Thermactor and EGR fully functional?

How many miles are on the engine?

Describe why it isn't 'running smooth'

What is it doing now?

I think any vacuum secondary carb between 600-750 can work well in one of these trucks.

Without knowing your objectives and budget it is hard to give an answer.

But my advice is always going to start with make sure you have a tight timing chain set straight up and do a thorough tune-up. (plugs, wires, cap, rotor, filters, check for any leaks and the ignition timing)

 

[Gary Lewis]

I definitely wouldn't use a carb with mechanical secondaries in a heavy truck on the street.

"Feels fast" and is fast are two different things.

"Like" is subjective. I like them all!

The 4180 probably metered best with the stock cam and all emissions in place.

The RV cam was a step backwards over the factory cam set straight up.

The 0-80457-S was a good replacement for the worn out 4180.

Do you use your truck for work? To tow?

Is it 4wd, and do you use it off road?

Automatic or manual transmission?

What axle ratio and tire size?

Do you have the stock cam, intake and exhaust manifolds?

Thermactor and EGR fully functional?

How many miles are on the engine?

Describe why it isn't 'running smooth'

What is it doing now?

I think any vacuum secondary carb between 600-750 can work well in one of these trucks.

Without knowing your objectives and budget it is hard to give an answer.

But my advice is always going to start with make sure you have a tight timing chain set straight up and do a thorough tune-up. (plugs, wires, cap, rotor, filters, check for any leaks and the ignition timing)

I know the question wasn't to me, but I can't help but add my two bits.

I tried both an Edelbrock 600 as well as the Edelbrock 750 on Big Blue's well worn 460 a couple of years ago. The 600 performed very well, and might have had a slight edge just off idle but the 750 had the edge on top end.

I say that add to what Jim has said. You need to determine what you are going to do with the truck and what other mods you are going to make. But unless you are going to spin the engine up quite a ways you won't need more than about 600 CFM in the carb.

[Fryeken]

I definitely wouldn't use a carb with mechanical secondaries in a heavy truck on the street.

"Feels fast" and is fast are two different things.

"Like" is subjective. I like them all!

The 4180 probably metered best with the stock cam and all emissions in place.

The RV cam was a step backwards over the factory cam set straight up.

The 0-80457-S was a good replacement for the worn out 4180.

Do you use your truck for work? To tow?

Is it 4wd, and do you use it off road?

Automatic or manual transmission?

What axle ratio and tire size?

Do you have the stock cam, intake and exhaust manifolds?

Thermactor and EGR fully functional?

How many miles are on the engine?

Describe why it isn't 'running smooth'

What is it doing now?

I think any vacuum secondary carb between 600-750 can work well in one of these trucks.

Without knowing your objectives and budget it is hard to give an answer.

But my advice is always going to start with make sure you have a tight timing chain set straight up and do a thorough tune-up. (plugs, wires, cap, rotor, filters, check for any leaks and the ignition timing)

Jim,

Thanks for the quick reply.

This truck was the two-tone red truck off eBay two years ago. The truck will run and drive, but struggles to stay running at idle. I also have to fill the bowls to get it started. Other home projects have gotten in the way and I didn’t want to start and not finish this truck. The plan is to keep the truck as a cruiser- not a work truck. Maybe some occasional towing.

I do need to start through the basics tune up wise- I do know that before throwing parts at it.

Interestingly, this truck still has the 1986 marked wires on it. So yeah, I’m sure the plugs are original as well. Odometer shows 51,000. Based on condition I’d say it’s probably accurate.

The truck as far as I can tell still has all the original smog equipment. Dual air pumps, stock manifolds with spider tubes are still there. Automatic, 4x4, 3.55 gears I believe with 33 12.50’s. I’ll confirm that again.

It does have the electric pump option, which I intend to check once I get the filter replaced, along with the tuneup and timing check.

Other than a timing swap for straight up, I plan to leave this truck alone as a survivor.

My goal is to be able to get in, hit the key and have it fire up and drive like it was or close to it was when new.

 

[ArdWrknTrk]

Jim,

Thanks for the quick reply.

This truck was the two-tone red truck off eBay two years ago. The truck will run and drive, but struggles to stay running at idle. I also have to fill the bowls to get it started. Other home projects have gotten in the way and I didn’t want to start and not finish this truck. The plan is to keep the truck as a cruiser- not a work truck. Maybe some occasional towing.

I do need to start through the basics tune up wise- I do know that before throwing parts at it.

Interestingly, this truck still has the 1986 marked wires on it. So yeah, I’m sure the plugs are original as well. Odometer shows 51,000. Based on condition I’d say it’s probably accurate.

The truck as far as I can tell still has all the original smog equipment. Dual air pumps, stock manifolds with spider tubes are still there. Automatic, 4x4, 3.55 gears I believe with 33 12.50’s. I’ll confirm that again.

It does have the electric pump option, which I intend to check once I get the filter replaced, along with the tuneup and timing check.

Other than a timing swap for straight up, I plan to leave this truck alone as a survivor.

My goal is to be able to get in, hit the key and have it fire up and drive like it was or close to it was when new.

The truck should fill the bowls while the starter is engaged.

So you need to check the fusible link to the 'I' terminal of the starter relay behind the battery.

If it still has the stock timing chain with nylon cam gear you probably want to address that before running it much.

It took me over an hour to pick the plastic shards out of my oil pickup, so the less you make the better.

If using EGR, stock cam and a stock distributor curve you're probably best to troubleshoot the 4180.

Because it only has 51k miles the plastic throttle shaft bushings are probably fine.

You can rebuild it with the 3-1346 kit, or one from Mike's carburetor parts.

I will add, be very careful about cross threading or overtightening the fuel inlet filter housing.

Always loosen and tighten the flare nut using a backup wrench.

If you strip the float bowl they are NLA.

 

[Fryeken]

The truck should fill the bowls while the starter is engaged.

So you need to check the fusible link to the 'I' terminal of the starter relay behind the battery.

If it still has the stock timing chain with nylon cam gear you probably want to address that before running it much.

It took me over an hour to pick the plastic shards out of my oil pickup, so the less you make the better.

If using EGR, stock cam and a stock distributor curve you're probably best to troubleshoot the 4180.

Because it only has 51k miles the plastic throttle shaft bushings are probably fine.

You can rebuild it with the 3-1346 kit, or one from Mike's carburetor parts.

I will add, be very careful about cross threading or overtightening the fuel inlet filter housing.

Always loosen and tighten the flare nut using a backup wrench.

If you strip the float bowl they are NLA.

Today I changed plugs, wires, cap, rotor. Set timing at 8 btdc. Found a slight leak at the fuel line inlet.

I pulled it apart and the brass filter looked new. I put a bit of antisieze on the threads and snugged it all back up. Thanks for the advice there Jim.

I need to check fuel pressure, but I set the choke and cranked it a bit and it eventually fired up and ran at a fast idle. I wanted to try this per procedure before starting to diag things.

After a few revs the truck stumbled and shut off. I’m planning to check the vacuum at idle and adjust the idle.

This truck came from Washington near Seattle and I’m at about 1200 above sea level. I’m thinking fuel needs backed off. Exhaust is sooty. Old plugs were black and dry.

I know, I know get it out and drive it.

Gary, a few pictures for you and the site.